Visualization of suppressed thyroid tissue by Tc-99m MIBI.

The authors describe a case of suppressed normal thyroid tissue in a patient with autonomous toxic nodule, which was visualized by a Tc-99m MIBI thyroid scan without thyrotropin (TSH) stimulation. The findings suggest that Tc-99m MIBI can be a substitute for conventional thyroid imaging using I-131 to visualize suppressed normal thyroid tissue without TSH stimulation and its side effects.     

Detection of cold bone metastasis by Tc-99m MIBI imaging

We present a case of renal cell carcinoma metastasis to the skull, appearing as a photopenic area on Tc-99m MDP bone scan and with focal uptake in the same region on Tc-99m MIBI imaging.     

Tc-99m MIBI imaging in malignant fibrous histiocytoma

The authors report a case of malignant fibrous histiocytoma of the left forearm demonstrated by Tc-99m MIBI imaging. The tumor originated in the soft tissue of the forearm; no obvious bone invasion or metastasis was detected scintigraphically or radiologically.     

Primary osteogenic sarcoma of breast detected on Tc-99m MIBI scintigraphy and Tc-99m MDP skeletal scintigraphy

A 64-year-old woman presented with a painless breast mass. Tc-99m methoxyisobutylisonitrile scintigraphy of both breasts showed a local area of abnormal uptake in the left breast in 5 min and 2 h. A skeletal scan showed very intense concentration of activity in the primary breast tumor in the left breast. A left mastectomy and an axillary dissection were performed. The predominant histologic type of the mass was an osteosarcoma, and the diagnosis of a primary osteogenic sarcoma of the breast was made. Primary osteogenic sarcoma of the breast is rare and represents less than 1% of all primary breast malignancies.     

Hepatic and splenic uptake of Tc-99m HDP in multiple myeloma: additional findings on Tc-99m MIBI and Tc-99m sulfur colloid images

The authors present a case of multiple myeloma with intense hepatic and splenic uptake on Tc-99m HDP bone scan and discuss its clinical implications and possible uptake mechanisms. Tc-99m MIBI and Tc-99m sulfur colloid were used to demonstrate bone marrow involvement and focal lesions of multiple myeloma.     

Tc-99m MIBI to evaluate children with Ewing's sarcoma

PURPOSE: Tc-99m MIBI has been used increasingly to evaluate benign and malignant tumors because of its tumor-seeking properties and ability to provide an imaging assessment of multiple-drug resistance. This study investigated the clinical utility of Tc-99m MIBI in the management of Ewing's sarcoma in children. METHODS: Thirteen Tc-99m MIBI studies in nine (six male, three female) patients ages 6.5 to 20 years (mean, 13.4 years) with Ewing's sarcoma were reviewed. All patients had imaging studies at diagnosis, and four had follow-up studies during or after therapy. Scintigraphy was evaluated for Tc-99m MIBI uptake within the tumor and in metastases, which other imaging modalities had shown to be present in four patients. Scintigraphic results were correlated with the clinical course in all patients and with tumor P-glycoprotein status in six patients. RESULTS: Tc-99m MIBI accumulated in 6 of 9 primary tumors and did not accumulate in one recurrent tumor. No metastases showed Tc-99m MIBI uptake. The presence or absence of Tc-99m MIBI uptake at diagnosis or after therapy carried no prognostic significance. Tc-99m MIBI was present in the two tumors that were P-glycoprotein positive and in only one of four tumors that were P-glycoprotein negative. CONCLUSION: Tc-99m MIBI imaging does not appear to be useful in Ewing's sarcoma.     

Simultaneous assessment of cardiac perfusion and function using 5-dimensional imaging with Tc-99m teboroxime

BACKGROUND: Dynamic single photon emission computed tomography (SPECT) acquisition and reconstruction of early poststress technetium 99m teboroxime washout images has been shown to be useful in the detection of coronary disease. Assessment of poststress regional wall motion may offer additional use in assessing coronary disease. Our goal was to investigate the feasibility of simultaneously imaging myocardial ischemia and transient poststress akinesis using gated-dynamic SPECT. METHODS AND RESULTS: A gated-dynamic mathematical cardiac torso (MCAT) phantom was developed to model both teboroxime kinetics and cardiac regional wall motion. A lesion was simulated as having delayed poststress teboroxime washout together with a transient poststress wall motion abnormality. Gated projection data were created to represent a 3-headed SPECT system undergoing a total rotation of 480 degrees . The dynamic expectation-maximization reconstruction algorithm with postsmoothing across gating intervals by Wiener filtering, and the ordered-subset expectation maximization reconstruction algorithm with 3-point smoothing across gating intervals were compared. Compared with the ordered-subset expectation maximization with 3-point smoothing, the dynamic expectation-maximization algorithm with Wiener filtering was able to produce visually higher-quality images and more accurate left ventricular ejection fraction estimates. CONCLUSION: From simulations, we conclude that changing cardiac function and tracer localization possibly can be assessed by using a gated-dynamic acquisition protocol combined with a 5-dimensional reconstruction strategy.     

Bone uptake of Tc-99m MIBI in patients with hyperparathyroidism

Objective

The study aimed to investigate the incidence of bone uptake of tracer on Tc-99m MIBI imaging and explore its influencing factors and significance for diagnosis of metabolic bone disease (MBD) in patients with hyperparathyroidism (HPT).

Methods

Seventy-nine consecutive patients with histopathologically confirmed HPT (63 primary and 16 secondary) who had preoperative Tc-99m MIBI imaging were retrospectively evaluated. Serum calcium (Ca), phosphorus (P), and intact parathyroid hormone (iPTH) were measured for all patients, and serum alkaline phosphatase (ALP) was measured for 62 patients. Of the 79 patients, 50 underwent bone mineral density (BMD) examination and 30 underwent bone scintigraphy. The incidence and characteristics of abnormal bone uptake of MIBI were recorded. Mann–Whitney test was performed to determine if serum iPTH, Ca, P, ALP, and BMD were different between the patients with and without MIBI bone uptake. Logistic regression analysis was used to analyze the factors that influence the bone uptake of MIBI. The concordance rate between Tc-99m MIBI imaging and bone scintigraphy in delineating MBD was calculated.

Results

Tc-99m MIBI imaging disclosed the abnormal bone uptake of tracer in 22 (27.8 %) patients. Of them, 19 showed diffusely increased activity in skeleton, 2 showed focal uptake in brown tumors, and one showed both above patterns. Patients with bone uptake MIBI had higher level of serum iPTH (Z = ?4.34, P < 0.001) and ALP (Z = ?3.50, P < 0.001) than those without bone uptake. Logistic regression analysis also showed that bone uptake of MIBI was correlated with serum iPTH (OR = 4.42, P < 0.001) and ALP (OR = 3.21, P = 0.002). Among the 30 patients that underwent bone scintigraphy, 76.7 % patients showed signs of MBD, and the concordance rate between Tc-99m MIBI imaging and bone scintigraphy was 60 % for detecting MBD.

Conclusions

Bone uptake of MIBI in patients with HPT is commonly related to a high level of iPTH and ALP; it probably reflects an active stage of MBD, and it should be monitored during the conventional Tc-99m MIBI scintigraphy.     

Biodistribution of Tc-99m methoxy-isobutyl-isonitrile (MIBI) in humans

Hexakis (methoxyisobutilisonitrile) technetium(I), ^99mTc-MIBI, has been proposed for myocardial perfusion studies. We have evaluated the biodistribution of this new agent in normal volunteers at rest and after stress. The biodistribution of ^99mTc-MIBI is characterized by rapid blood clearance and a consequently early myocardial uptake. The initial intense hepatic activity is cleared into the gallbladder at 1 h after injection, and the best target to non target ratio is observed at 60–90 min after injection. Absorbed radiation dose calculations show that the thyroid is the critical target organ (230 mRad/mCi at rest), presumably because of ^99mTc-pertechnetate generated in vivo. Our results indicate that ^99mTc-MIBI is a promising tracer for myocardial perfusion imaging.     

Biodistribution of Tc-99m methoxy-isobutyl-isonitrile (MIBI) in humans

Hexakis (methoxyisobutilisonitrile) technetium(I), 99mTc-MIBI, has been proposed for myocardial perfusion studies. We have evaluated the biodistribution of this new agent in normal volunteers at rest and after stress. The biodistribution of 99mTc-MIBI is characterized by rapid blood clearance and a consequently early myocardial uptake. The initial intense hepatic activity is cleared into the gallbladder at 1 h after injection, and the best target to non target ratio is observed at 60-90 min after injection. Absorbed radiation dose calculations show that the thyroid is the critical target organ (230 mRad/mCi at rest), presumably because of 99mTc-pertechnetate generated in vivo. Our results indicate that 99mTc-MIBI is a promising tracer for myocardial perfusion imaging.     

Reverse of the differential uptake intensity of Tc-99m MIBI and Tc-99m V-DMSA by multiple myeloma lesions in response to therapy

PURPOSE: The objective of this study was to compare the uptake changes of Tc-99m 2-methoxy isobutyl isonitrile (MIBI) and Tc-99m pentavalent dimercaptosuccinic acid (V-DMSA) in multiple myeloma (MM) lesions in response to high-dose chemotherapy (HDC). MATERIALS AND METHODS: The authors compared Tc-99m MIBI and Tc-99m V-DMSA scans before and after HDC in a patient with focal MM lesions without amyloidosis who had received previous standard chemotherapy as well. RESULTS: HDC had the effect of eliminating all Tc-99m MIBI uptake in the lesions. Tc-99m V-DMSA uptake was increased in lesions presenting significant initial Tc-99m MIBI uptake. In 1 particular lesion that demonstrated this phenomenon, magnetic resonance showed necrosis of the area of MM. CONCLUSION: The authors consider that the effect of increasing Tc-99m V-DMSA uptake in the absence of an increase in viable plasma cells possibly reflects the treatment-generated inflammatory and fibrotic changes and not necessarily viable tumor tissue. Exclusive focal Tc-99m V-DMSA uptake in this clinical setting could be considered as a sign of effectively treated lesions and not a sign of deterioration.     

Simultaneous technetium-99m MIBI angiography and myocardial perfusion imaging

Resting first-pass radionuclide angiography (FPRNA) was performed with the myocardial perfusion agent technetium-99m MIBI. In 27 patients, it was compared with technetium-99m diethylenetriamine pentaacetic acid FPRNA. A significant correlation was present in left (r = 0.93, p less than 0.001) as well as right (r = 0.92, p less than 0.001) ventricular ejection fraction measured with both radiopharmaceuticals. In 13 patients, MIBI derived segmental wall motion was compared with contrast ventriculography. A high correlation was present (p less than 0.001), and qualitative agreement was found in 38/52 segments. In 19 patients with myocardial infarction a significant correlation was present between MIBI segmental wall motion and perfusion scores (p less than 0.001). In ten patients with a history of myocardial infarction, 18 myocardial segments demonstrated diseased coronary vessels and impaired wall motion at contrast angiography. These segments were all identified by the MIBI wall motion and perfusion study. We conclude that MIBI is a promising agent for simultaneous evaluation of cardiac function and myocardial perfusion at rest.